The throughput of a parallel distribution processing executed by parallel computer may be enhanced by improving the communication efficiency in the parallel computer through an optimization of a connection form of a server and a switch (i.e., network topology) in the parallel computer. In addition, when a large number of servers are connected with a small number of switches by an optimization of the network topology in the parallel computer, the construction cost of the parallel computer may be suppressed.
A network topology where each node in a network is directly connected to any of the other nodes is called a full mesh topology. A system adopting a structure in which each switch is directly connected to each of other switches (hereinafter, referred to as a full mesh system) is known. Further, a system in which a plurality of full mesh systems is connected by a spine switch is known. According to the technique, it is possible to avoid a route contention at the time of an all-to-all communication in the full mesh system. Here, the route contention indicates that a plurality of packets is transmitted simultaneously in the same direction of one route.
However, in the parallel computer, depending on a type of a job, a communication other than the all-to-all communication may be performed. As for the communication other than the all-to-all communication, for example, an all-reduce communication is known. The all-reduce communication refers to a communication in which all target nodes hold the result of an operation executed using data possessed by all of the target nodes, and the name of “all-reduce” refers to an operation thereof. Since the technique described above is directed to the all-to-all communication, the route contention may not be avoided at the time of executing the all-reduce communication.
Related technologies are disclosed in, for example, Japanese Patent Laid-Open Publication No. 2015-232874.